True, and yet nearly every original bitcoin millionaire became one specifically because they decided to mine something that was worthless at the time. Sometimes you don't have money, but you have a GPU and someone else is paying for your electricity. I understand that doesn't describe most mining these days, but the point still stands: people will speculate at a loss.
Again, you're confusing "mining" (economic activity that produces new coins and fees that happen to be measured in BTC) with "investment" (acquiring BTC via any means with the intent to hold).
They are not the same concept, in fact they're completely orthogonal. You don't mine to get coins for investment, because you can get coins much (MUCH!) more cheaply via other means. You mine to get income in the present.
No, mining is economic activity, not investment. You pay stuff to get stuff. Whether you then invest your profits in crypto has nothing to do with where you got them.